Fluoropolymer coating compositions comprising amine curing agents, coated substrates and related methods

ABSTRACT

Compositions are described comprising at least one fluoropolymer, a solvent and an amino compound. The fluoropolymer comprises at least 90% by weight based on the total weight of the fluoropolymer of polymerized units derived from perfluorinated monomers selected from tetrafluoroethene (TFE) and one or more unsaturated perfluorinated alkyl ethers. The fluoropolymer typically comprises one or more cure sites, such as nitrile or halogenated cure sites. The solvent typically comprises a branched, partially fluorinated ether. In preferred embodiments the amine compound further comprises a silane group. Also described are methods of making the coating composition, methods of coating a substrate with UV and/or thermal curing, and the coated substrate.

SUMMARY

In one embodiment, a composition is described comprising at least onefluoropolymer, wherein the fluoropolymer comprises at least 90% byweight based on the total weight of the fluoropolymer of polymerizedunits derived from perfluorinated monomers selected fromtetrafluoroethene (TFE) and one or more unsaturated perfluorinated alkylethers; a solvent comprising a branched, partially fluorinated ether andwherein the partially fluorinated ether corresponds to the formula:

Rf—O—R

wherein Rf is a selected from perfluorinated and partially fluorinatedalkyl or (poly)ether groups and R is selected from partially fluorinatedand non-fluorinated alkyl groups; and a compound comprising at least oneamine group and at least one organosilane group.

In another embodiment, a composition is described comprises at least onefluoropolymer, wherein the fluoropolymer comprises at least 90% byweight based on the total weight of the fluoropolymer of polymerizedunits derived from perfluorinated monomers selected fromtetrafluoroethene (TFE) and one or more unsaturated perfluorinated alkylethers; and one or more cure sites selected from nitrile, iodine,bromine, or a combination thereof; a fluorinated solvent; and a compoundcomprising at least one amine group and at least one silane group.

In other embodiments, methods of making (fluorinated solvent-based)compositions are described comprising dissolving the fluoropolymer inthe solvent and adding the curing agent subsequently, concurrently, orafter dissolving the fluoropolymer in the solvent.

In another embodiment, a substrate comprising a coated surface isdescribed wherein the surface comprises a crosslinked fluoropolymer,wherein the fluoropolymer comprises at least 90% by weight based on thetotal weight of the fluoropolymer of polymerized units derived fromperfluorinated monomers selected from tetrafluoroethene (TFE) and one ormore unsaturated perfluorinated alkyl ethers; and one or more cure sitesselected from nitrile, iodine, bromine, or a combination thereof; and acompound comprising at least one amine group and at least one silanegroup.

In another embodiment, a polymer sheet is described comprising afluoropolymer wherein the fluoropolymer comprises at least 90% by weightbased on the total weight of the fluoropolymer of polymerized unitsderived from perfluorinated monomers selected from tetrafluoroethene(TFE) and one or more unsaturated perfluorinated alkyl ethers; and oneor more cure sites selected from nitrile, iodine, bromine, or acombination thereof; and a compound comprising at least one amine groupand at least one silane group.

In another embodiment, a method of making a coated substrate isdescribed comprising i) applying a coating composition to a substratewherein the coating composition comprises at least one fluoropolymer,wherein the fluoropolymer comprises cure sites and at least 90% byweight based on the total weight of the fluoropolymer of polymerizedunits derived from perfluorinated monomers selected fromtetrafluoroethene (TFE) and one or more unsaturated perfluorinated alkylethers; fluorinated solvent, and an amine curing agent; ii) removing thesolvent; and iii) curing the fluoropolymer at a temperature ranging from135° C. to 170° C. concurrently or prior to removing the solvent.

In another embodiment, a method of making a coated substrate isdescribed comprising i) applying a coating composition to a substratewherein the coating composition comprises at least one fluoropolymer,wherein the fluoropolymer comprises cure sites selected from iodine,bromine, and chlorine and at least 90% by weight based on the totalweight of the fluoropolymer of polymerized units derived fromperfluorinated monomers selected from tetrafluoroethene (TFE) and one ormore unsaturated perfluorinated alkyl ethers; fluorinated solvent, andan amine curing agent; ii) removing the solvent; and iii) curing thefluoropolymer with ultraviolet radiation.

DETAILED DESCRIPTION

Presently described are coating compositions comprising certainfluoropolymers and a fluorinated solvent, coated substrates, and methodsof making the compositions and the coated substrates.

The fluoropolymers described herein are copolymers that comprisepredominantly, or exclusively, (e.g. repeating) polymerized unitsderived from two or more perfluorinated comonomers. Copolymer refers toa polymeric material resulting from the simultaneous polymerization oftwo or more monomers. The comonomers include tetrafluoroethene (TFE) andone or more unsaturated perfluorinated (e.g. alkenyl, vinyl) alkylethers.

In some favored embodiments, the one or more unsaturated perfluorinatedalkyl ethers are selected from the general formula:

R_(f)—O—(CF₂)_(n)—CF═CF₂

wherein n is 1 (allyl ether) or 0 (vinyl ether) and R_(f) represents aperfluoroalkyl residue which may be interrupted once or more than onceby an oxygen atom. R_(f) may contain up to 10 carbon atoms, e.g. 1, 2,3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms. Preferably R_(f) contains up to8, more preferably up to 6 carbon atoms and most preferably 3 or 4carbon atoms. In one embodiment R_(f) has 3 carbon atoms. In anotherembodiment R_(f) has 1 carbon atom. R_(f) may be linear or branched, andit may contain or not contain a cyclic unit. Specific examples of Rfinclude residues with one or more ether functions including but notlimited to:—(CF₂)—O—C₃F₇,—(CF₂)₂—O—C₂F₅,—(CF₂)_(r3)—O—CF₃,—(CF₂—O)—C₃F₇,—(CF₂—O)₂—C₂F₅,—(CF₂—O)₃—CF₃,—(CF₂CF₂—O)—C₃F₇,—(CF₂CF₂—O)₂—C₂F₅,—(CF₂CF₂—O)₃—CF₃,

Other specific examples for R_(f) include residues that do not containan ether function and include but are not limited to —C₄F₉, —C₃F₇,—C₂F₅, —CF₃, wherein the C₄ and C₃ residues may be branched or linear,but preferably are linear.

Specific examples of suitable perfluorinated alkyl vinyl ethers (PAVE's)and perfluorinated alkyl allyl ethers (PAAE's) include but are notlimited to perfluoro (methyl vinyl) ether (PMVE), perfluoro (ethylvinyl) ether (PEVE), perfluoro (n-propyl vinyl) ether (PPVE-1),perfluoro-2-propoxypropylvinyl ether (PPVE-2),perfluoro-3-methoxy-n-propylvinyl ether, perfluoro-2-methoxy-ethylvinylether, CF₂═CF—O—CF₂—O—C₂F₅, CF₂═CF—O—CF₂—O—C₃F₇,CF₃—(CF₂)₂—O—CF(CF₃)—CF₂—O—CF(CF₃)—CF₂—O—CF═CF₂ and their allyl etherhomologues. Specific examples of allyl ethers include CF₂═CF—CF₂—O—CF₃,CF₂═CF—CF₂—O—C₃F₇, CF₂═CF—CF₂—O—(CF₃)₃—O—CF₃.

Further examples include but are not limited to the vinyl etherdescribed in European patent application EP 1,997,795 B1.

Perfluorinated ethers as described above are commercially available, forexample from Anles Ltd., St. Petersburg, Russia and other companies ormay be prepared according to methods described in U.S. Pat. No.4,349,650 (Krespan) or European Patent 1,997,795, or by modificationsthereof as known to a skilled person.

The fluoropolymers are derived predominantly or exclusively fromperfluorinated comonomers including tetrafluoroethene (TFE) and one ormore of the unsaturated perfluorinated alkyl ethers described above.“Predominantly” as used herein means at least 90% by weight based on thetotal weight of the fluoropolymer, of the polymerized units of thefluoropolymer are derived from such perfluorinated comonomers. In someembodiments, the fluoropolymer comprises at least 91, 92, 93, 94, 95,96, or 97% by weight or greater of such perfluorinated comonomers, basedon the total weight of the fluoropolymer. The fluoropolymers may containat least 40, 45, or 50% by weight of polymerized units derived from TFE.In some embodiments, the maximum amount of polymerized units derivedfrom TFE is no greater than 60% by weight.

The fluoropolymer typically comprises polymerized units derived from oneor more of the unsaturated perfluorinated alkyl ethers (such as PMVE,PAVE, PAAE or a combination thereof) in an amount of at least 10, 15,20, 25, 30, 45, or 50% by weight, based on the total polymerized monomerunits of the fluoropolymer. In some embodiments, the fluoropolymercomprises no greater than 50, 45, 40, or 35% by weight of polymerizedunits derived from one or more of the unsaturated perfluorinated alkylethers (such as PMVE, PAVE, PAAE or a combination thereof), based on thetotal polymerized monomer units of the fluoropolymer. The molar ratio ofunits derived from TFE to the perfluorinated alkly ethers describedabove may be, for example, from 1:1 to 5:1. In some embodiments, themolar ratio ranges from 1.5:1 to 3:1.

In other embodiments, the fluoropolymer comonomers comprisepredominantly, or exclusively comprise, (e.g. repeating) polymerizedunits derived from two or more perfluorinated comonomers includingtetrafluoroethene (TFE) and one or more unsaturated cyclicperfluorinated alkyl ethers, such as2,2-bistrifluoromethyl-4,5-difluoro-1,3 dioxole. Such fluoropolymers arecommercially available as “TEFLON™ AF”, “CYTOP™”, and “HYFLON™”.

The fluoropolymers may be thermoplastic but, in a preferred embodiment,the fluoropolymer is amorphous. As used herein, amorphous fluoropolymersare materials that contain essentially no crystallinity or possess nosignificant melting point (peak maximum) as determined by differentialscanning calorimetry in accordance with DIN EN ISO 11357-3:2013-04 undernitrogen flow

and a heating rate of 10° C./min. Typically, amorphous fluoropolymershave a glass transition temperature (Tg) of less than 26° C., less than20° C., or less than 0° C., and for example from −40° C. to 20° C., or−50° C. to 15° C., or −55° C. to 10° C. The fluoropolymers may typicallyhave a Mooney viscosity (ML 1+10 at 121° C.) of from about 2 to about150, for example from 10 to 100, or from 20 to 70. For amorphouspolymers containing cyclic perfluorinated alky ether units, the glasstransition temperature is typically at least 70° C., 80° C., or 90° C.,and may range up to 220° C., 250° C., 270° C., or 290° C. The MFI (297°C./5 kg) is between 0.1-1000 g/10 min.

The fluoropolymer is preferably a curable fluoropolymer that containsone or more cure sites. Cure sites are functional groups that react inthe presence of a curing agent or a curing system to cross-link thepolymers. The cure sites are typically introduced by copolymerizingcure-site monomers, which are functional comonomers already containingthe cure sites or precursors thereof. The cure sites react with an aminecuring agent thereby crosslinking (curing) the fluoropolymer. Oneindication of crosslinking is that the dried and cured coatingcomposition was not soluble in the fluorinated solvent of the coating.

The cure sites may be introduced into the polymer by using cure sitemonomers, i.e. functional monomers as will be described below,functional chain-transfer agents and starter molecules. Thefluoroelastomers may contain cure sites that are reactive to more thanone class of curing agents. An example widely used in the art includescure sites containing nitrile or nitrile groups. Such cure sites arereactive, for example, to amine curing agent, as well as peroxide curingagents.

The curable fluoroelastomers may also contain cure sites in the backboneor as pending groups in addition, or as an alternative to the cure sitesat a terminal position. Cure sites within the fluoropolymer backbone canbe introduced by using a suitable cure-site monomer. Cure site monomersare monomers containing one or more functional groups that can act ascure sites or contain a precursor that can be converted into a curesite.

In some embodiments, the cure sites comprise iodine or bromine atoms.

Iodine-containing cure site end groups can be introduced by using aniodine-containing chain transfer agent in the polymerization.Iodine-containing chain transfer agents will be described below ingreater detail. Halogenated redox systems as described below may be usedto introduce iodine end groups.

In addition to iodine cures sites, other cure sites may also be present,for example Br-containing cure sites or cure sites containing one ormore nitrile groups. Br-containing cure sites may be introduced byBr-containing cure-site monomers. Nitrile-containing cure sites aretypically introduced by cure site monomers containing a nitrile group.

Examples of cure-site comonomers include for instance:

(a) bromo- or iodo-(per)fluoroalkyl-(per)fluorovinylethers, for exampleincluding those having the formula:

ZRf—O—CX═CX₂

wherein each X may be the same or different and represents H or F, Z isBr or I, Rf is a C1-C12 (per)fluoroalkylene, optionally containingchlorine and/or ether oxygen atoms. Suitable examples includeZCF₂—O—CF═CF₂, ZCF₂CF₂—O—CF═CF₂, ZCF₂CF₂CF₂—O—CF═CF₂, CF₃CFZCF₂—O—CF═CF₂or ZCF₂CF₂—O—CF₂CF₂CF₂—O—CF═CF₂ wherein Z represents Br of I; and(b) bromo- or iodo perfluoroolefins such as those having the formula:

Z′—(Rf)_(r)—CX═CX₂

wherein each X independently represents H or F, Z′ is Br or I, Rf is aC₁-C₁₂ perfluoroalkylene, optionally containing chlorine atoms and r is0 or 1; and(c) non-fluorinated bromo and iodo-olefins such as vinyl bromide, vinyliodide, 4-bromo-1-butene and 4-iodo-1-butene.

Specific examples include but are not limited to compounds according to(b) wherein X is H, for example compounds with X being H and Rf being aC1 to C3 perfluoroalkylene. Particular examples include: bromo- oriodo-trifluoroethene, 4-bromo-perfluorobutene-1,4-iodo-perfluorobutene-1, or bromo- or iodo-fluoroolefins such as1-iodo,2,2-difluroroethene, 1-bromo-2,2-difluoroethene,4-iodo-3,3,4,4,-tetrafluorobutene-1 and4-bromo-3,3,4,4-tetrafluorobutene-1;6-iodo-3,3,4,4,5,5,6,6-octafluorohexene-1.

In some embodiments, the cure sites comprise chlorine atoms. Suchcure-site monomers include those of the general formula: CX₁X₂═CY₁Y₂where X₁, X₂ are independently H and F; Y₁ is H, F, or Cl; and Y₂ is Cl,a fluoroalkyl group (R_(F)) with at least one Cl substituent, afluoroether group (OR_(F)) with at least one Cl substituent, or—CF₂—OR_(F). The fluoroalkyl group (R_(F)) is typically a partially orfully fluorinated C₁-C₅ alkyl group. Examples of cure-site monomer withchlorine atoms include CF₂═CFCl, CF₂═CF—CF₂C₁, CF₂═CF—O—(CF₂)_(n)—C₁,n=1-4; CH₂═CHCl, CH₂═CCl₂.

Typically, the amount of iodine or bromine or chlorine or theircombination in the fluoropolymer is between 0.001 and 5%, preferablybetween 0.01 and 2.5%, or 0.1 to 1% or 0.2 to 0.6% by weight withrespect to the total weight of the fluoropolymer. In one embodiment thecurable fluoropolymers contain between 0.001 and 5%, preferably between0.01 and 2.5%, or 0.1 to 1%, more preferably between 0.2 to 0.6% byweight of iodine based on the total weight of the fluoropolymer. In someembodiments, the curable fluoropolymer contains nitrile-containing curesites, as a alternative or in addition to the I- and/or Br-cure sitesdescribed above. Fluoropolymers with nitrile-containing cure sites areknown, such as described in U.S. Pat. No. 6,720,360.

Nitrile-containing cure sites may be reactive to other cure systems forexample, but not limited to, bisphenol curing systems, peroxide curingsystems, triazine curing systems, and especially amine curing systems.Examples of nitrile containing cure site monomers correspond to thefollowing formulae:

CF₂═CF—CF₂—O—Rf—CN;

CF₂═CFO(CF₂)_(r)CN;

CF₂═CFO[CF₂CF(CF₃)O]_(p)(CF₂)_(v)OCF(CF₃)CN;

CF₂═CF[OCF₂CF(CF₃)]_(k)O(CF₂)_(u)CN;

wherein, r represents an integer of 2 to 12; p represents an integer of0 to 4; k represents 1 or 2; v represents an integer of 0 to 6; urepresents an integer of 1 to 6, Rf is a perfluoroalkylene or a bivalentperfluoroether group. Specific examples of nitrile containingfluorinated monomers include but are not limited to perfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene), CF₂═CFO(CF₂)₅CN, andCF₂═CFO(CF₂)₃₀CF(CF₃)CN.

The amount of units derived from nitrile-containing cure site comonomersdepends on the desired crosslinking density. The amount ofnitrile-containing cure site comonomer is typically at least 0.5, 1,1.5, 2, 2.5, 3. 3.5, 4, 4.5 or 5% by weight and typically no greaterthan 10% by weight; based on the total weight of the fluoropolymer. Thefluoropolymers may also be of dual cure type, containing different curesites that are reactive to different curing systems.

It is contemplated that by using halogenated chain transfer agents,terminal cure sites may be introduced. Chain transfer agents arecompounds capable of reacting with the propagating polymer chain andterminating the chain propagation. Examples of chain transfer agentsreported for the production of fluoroelastomers include those having theformula Rh, wherein R is an x-valent fluoroalkyl or fluoroalkyleneradical having from 1 to 12 carbon atoms, which, may be interrupted byone or more ether oxygens and may also contain chlorine and/or bromineatoms. R may be Rf and Rf may be an x-valent (per)fluoroalkyl or(per)fluoroalkylene radical that may be interrupted once or more thanonce by an ether oxygen. Examples include alpha-omega diiodo alkanes,alpha-omega diiodo fluoroalkanes, and alpha-omegadiiodoperfluoroalkanes, which may contain one or more catenary etheroxygens. “Alpha-omega” denotes that the iodine atoms are at the terminalpositions of the molecules. Such compounds may be represented by thegeneral formula X—R—Y with X and Y being I and R being as describedabove. Specific examples include di-iodomethane, alpha-omega (or 1,4-)diiodobutane, alpha-omega (or 1,3-) diiodopropane, alpha-omega (or 1,5-)diiodopentane, alpha-omega (or 1,6-) diiodohexane and1,2-diiodoperfluoroethane. Other examples include fluorinated di-iodoether compounds of the following formula:

R_(f)—CF(I)—(CX₂)_(n)—(CX₂CXR)_(m)—O—R″f-O_(k)—(CXR′CX₂)_(p)—(CX₂)_(q)—CF(I)—R′_(f)

wherein X is independently selected from F, H, and C₁; R_(f) and R′_(f)are independently selected from F and a monovalent perfluoroalkanehaving 1-3 carbons; R is F, or a partially fluorinated or perfluorinatedalkane comprising 1-3 carbons; R″_(f) is a divalent fluoroalkylenehaving 1-5 carbons or a divalent fluorinated alkylene ether having 1-8carbons and at least one ether linkage; k is 0 or 1; and n, m, and p areindependently selected from an integer from 0-5, wherein, n plus m atleast 1 and p plus q are at least 1.

The fluoropolymers may or may not contain units derived from at leastone modifying monomer. The modifying monomers may introduce branchingsites into the polymer architecture. Typically, the modifying monomersare bisolefins, bisolefinic ethers or polyethers. The bisolefins andbisolefinic (poly)ethers may be perfluorinated, partially fluorinated ornon-fluorinated. Preferably they are perfluorinated. Suitableperfluorinated bisolefinic ethers include those represented by thegeneral formula:

CF₂═CF—(CF₂)_(n)—O—(Rf)—O—(CF₂)_(m)—CF═CF₂

wherein n and m are independent from each other either 1 or 0 andwherein Rf represents a perfluorinated linear or branched, cyclic oracyclic aliphatic or aromatic hydrocarbon residue that may beinterrupted by one or more oxygen atoms and comprising up to 30 carbonatoms. A particular suitable perfluorinated bisolefinic ether is adi-vinylether represented by the formula:

CF₂═CF—O—(CF₂)_(n)—O—CF═CF₂

wherein n is an integer between 1 and 10, preferably 2 to 6, e.g. n maybe 1, 2, 3, 4, 5, 6 or 7. More preferably, n represents an uneveninteger, for example 1, 3, 5 or 7.

Further specific examples include bisolefinic ethers according thegeneral formula

CF₂═CF—(CF₂)_(n)—O—(CF₂)_(p)—O—(CF₂)_(m)—CF═CF₂

wherein n and m are independently either 1 or 0 and p is an integer from1 to 10 or 2 to 6. For example, n may be selected to represent 1, 2, 3,4, 5, 6 or 7, preferably, 1, 3, 5 or 7.

Further suitable perfluorinated bisolefinic ethers can be represented bythe formula

CF₂═CF—(CF₂)_(p)—O—(R_(af)O)_(n)(R_(bf)O)_(m)—(CF₂)_(q)—CF═CF₂

wherein R_(af) and R_(bf) are different linear or branchedperfluoroalkylene groups of 1-10 carbon atoms, in particular, 2 to 6carbon atoms, and which may or may not be interrupted by one or moreoxygen atoms. R_(af) and/or R_(bf) may also be perfluorinated phenyl orsubstituted phenyl groups; n is an integer between 1 and 10 and m is aninteger between 0 and 10, preferably m is 0. Further, p and q areindependent from each other either 1 or 0.

Such modifiers can be prepared by methods known in the art and arecommercially available, for example, from Anles Ltd., St. Petersburg,Russia.

Preferably, the modifiers are not used or only used in low amounts.Typical amounts include from 0 to 5%, or from 0 to 1.4% by weight basedon the total weight of the fluoropolymer. Modifiers may be present, forexample, in amounts from about 0.1% to about 1.2% or from about 0.3% toabout 0.8% by weight based on the total weight of fluoropolymer.Combinations of modifiers may also be used.

The fluoropolymers may contain partially fluorinated or non-fluorinatedcomonomers and combinations thereof, although this is not preferred.Typical partially fluorinated comonomers include but are not limited to1,1-difluoroethene (vinylidenefluoride, VDF) and vinyl fluoride (VF) ortrifluorochloroethene or trichlorofluoroethene. Examples ofnon-fluorinated comonomers include but are not limited to ethene andpropene. The amount of units derived from these comonomers include from0 to 8% by weight based on the total weight of the fluoropolymer. Insome embodiments, the concentration of such comonomer is no greater than7, 6, 5, 4, 3, 2, or 1% by weight based on the total weight of thefluoropolymer.

In a particularly preferred embodiment, the curable fluoropolymer is aperfluoroelastomer that comprises repeating units (exclusivel)y derivedfrom the perfluorinated comonomers but may contain units derived fromcure-site monomers, and modifying monomers if desired. The cure-sitemonomers and modifying monomers may be partially fluorinated, notfluorinated or perfluorinated, and preferably are perfluorinated. Theperfluoroelastomers may contain from 69 to 73, 74, or 75% fluorine byweight (based on the total amount of perfluoroelastomer). The fluorinecontent may be achieved by selecting the comonomers and their amountsaccordingly.

Such highly-fluorinated amorphous fluoropolymers typically do notdissolve to the extent of at least 1 wt. %, at room temperature andstandard pressure, in a hydrogen-containing organic liquid (e.g., itdoes not dissolve in any of methyl ethyl ketone (“MEK”), tetrahydrofuran(“THF”), ethyl acetate or N-methyl pyrrolidinone (“NMP”)).

The fluoropolymers can be prepared by methods known in the art, such asbulk, suspension, solution or aqueous emulsion polymerisation. Forexample, the polymerisation process can be carried out by free radicalpolymerization of the monomers alone or as solutions, emulsions, ordispersions in an organic solvent or water. Seeded polymerizations mayor may not be used. Curable fluoroelastomers that can be used alsoinclude commercially available fluoroelastomers, in particularperfluoroelastomers.

The fluoropolymers may have a monomodal or bi-modal or multi-modalweight distribution. The fluoropolymers may or may not have a core-shellstructure. Core-shell polymers are polymers where towards the end of thepolymerization, typically after at least 50% by mole of the comonomersare consumed, the comonomer composition or the ratio of the comonomersor the reaction speed is altered to create a shell of differentcomposition.

The fluoropolymer compositions described herein contain one or morecuring agents including at least one amine curing agent.

Suitable curing agents for nitrile cure sites are known in the art andinclude, but are not limited to amidines, amidoximes and othersdescribed in WO2008/094758 A1, incorporated herein by reference. Suchcuring agents include nitrogen-containing nucleophilic compoundsselected from heterocyclic secondary amines; guanidines; compounds whichdecompose in-situ at a temperature between 40° C. and 330″C to produce aguanidine; compounds which decompose in-situ at a temperature between40° C. and 330° C. to produce a primary or secondary amine; nucleophiliccompounds of the formula R₁—NH—R₂, wherein R₁ is H—, a C₁-C₁₀ aliphatichydrocarbon group, or an aryl group having hydrogen atoms in the alphapositions, R₇ is a C₁-C₁₀ aliphatic hydrocarbon group, an aryl grouphaving hydrogen atoms in the alpha positions, —CONHR₃, —NHCO₂R₃, or—OH′, and R₃ is a C₁-C₁₀ aliphatic hydrocarbon group; and substitutedamidines of the formula HN═CR₄NR₅R₆, wherein R₄, R₅, R₆ areindependently H—, alkyl or aryl groups and wherein at least one of R₄,R₅ and R₆ is not H—.

As used herein, “heterocyclic secondary amine” refers to aromatic oraliphatic cyclic compound having at least one secondary amine nitrogencontained within the ring. Such compounds include, for example, pyrrole,imidazole, pyrazole, 3-pyrroline, and pyrrolidine.

Guanidines included in this disclosure are compounds derived fromguanidine, i.e. compounds which contain the radical, —NHCNHNH—, such as,but not limited to, diphenylguanidine, diphenylguanidine acetate,aminobutylguanidine, biguanidine, isopentsilguanidine,di-σ-tolylguanidine, o-tolylbiguanide, and triphenylguanidine.

In some embodiments, the curing agent is a compound that decomposesin-situ at a temperature between 40° C. and 330° C. to produce either aprimary or secondary amine include, but are not limited to, di- orpoly-substituted ureas (e.g. 1,3-dimethyl urea); N-alkyl or -dialkylcarbamates (e.g. N-(tert-butyloxycarbonyl)propylamine); di- orpoly-substituted thioureas (e.g. 1,3-dimethyl-thiourea); aldehyde-aminecondensation products (e.g. 1,3,5-trimethylhexahydro-1,3,5-triazine);N,N′-dialkyl phthalamide derivatives (e.g. N,N′-dimethylphthalamide);and amino acids.

Illustrative examples of nucleophilic compounds of formula R₁—NH—R₂include, but are not limited to, aniline, t-butylcarbazate and C₁-C₁₀aliphatic primary amines (such as methylamine). Illustrative examples ofsubstituted amidines of the formula HN═CR₄NR₅R₆ include benzamidine andN-phenyl benzamidine.

In another embodiment, the amine curing agent is an aromatic oraliphatic cyclic compound having at least one tertiary amine nitrogencontained within the ring, or in other words a “heterocyclic tertiaryamine.” One such compound is 1,8-diazabicyclo [5.4.0] unde-7-ene.

It is surmised that most of these nucleophilic compounds act as curingagents by catalyzing the trimerization of polymer chain bound nitrilegroups to form triazine rings, thus crosslinking the fluoroelastomer.

Another type of amine curing agent includes bis(aminophenols) andbis(aminothiophenols) of the formulae

where A is SO₂, O, CO, alkyl of 1-6 carbon atoms, perfluoroalkyl of 1-10carbon atoms, or a carbon-carbon bond linking the two aromatic rings.The amino and hydroxyl groups in the above formulas are interchangeablyin the meta and para positions with respect to group A. Preferably, thesecond curing agent is a compound selected from the group consisting of2,2-bis[3-amino-4-hydroxyphenyljhexafiuoropropane;4,4′-sulfonylbis(2-aminophenol); 3,3-diaminobenzidine; and3,3′,4,4-tetraaminobenzophenone. The first of these curing agents arereferred to as diaminobisphenol AF. The curing agents can be prepared asdisclosed in U.S. Pat. No. 3,332,907 to Angelo. Diaminobisphenol AF canbe prepared by nitration of4,4′-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bisphenol (i.e.bisphenol AF), preferably with potassium nitrate and trifluoroaceticacid, followed by catalytic hydrogenation, preferably with ethanol as asolvent and a catalytic amount of palladium on carbon as catalyst.

In some embodiments, the (e.g. bis(aminophenols) andbis(aminothiophenols) are used in combination with an organotincompound. Suitable organotin compounds include allyl-, propargyl-,triphenyl- and allenyl tin curatives.

In some embodiments, the amine curing agent is an aliphatic diamine,such as ethylene diamine.

In some embodiments, the amine curing agent is an aziridine compound.

In some embodiments, the aziridine compound comprises at least twoaziridine groups. The aziridine compound may comprise 3, 4, 5, 6, orgreater than 6 aziridine groups. The aziridine compound may berepresented by the following structure:

wherein R is a core moiety having a valency of Y;L is a bond, divalent atom, or divalent linking group;R₁; R₂, R₃, and R₄ are independently hydrogen or a C₁-C₄ alkyl (e.g.methyl); andY is typically 2, 3, or greater.

In some embodiments, R is —SO₂—. In some embodiments, R-L is a residueof a multi(meth)acrylate compound. In some embodiments L is a C₁-C₄alkylene, optionally substituted with one or more (e.g. contiguous orpendant) oxygen atoms thereby forming ether or ester linkages. Intypical embodiments, R₁ is methyl and R₂, R₃, and R₄ are hydrogen.

Representative aziridine compounds include trimethylolpropanetri-[beta-(N-aziridinyl)-propionate, 2,2-bishydroxymethylbutanoltris[3-(1-aziridine) propionate];1-(aziridin-2-yl)-2-oxabut-3-ene; and 4-(aziridin-2-yl)-but-1-ene; and5-(aziridin-2-yl)-pent-1-ene.

In some embodiments, a polyaziridine compound can be prepared byreacting divinyl sulfone with alkylene (e.g. ethylene) imine, such asdescribed in U.S. Pat. No. 3,235,544 (Christena). On representativecompound is di(2-propyleniminoethyl)sulfone, as depicted as follows:

The above described polyaziridine compounds comprise at least twoaziridine groups at the time the compound is added to the coatingcomposition. In other embodiments, the polyaziridine compound does notcomprise two aziridine groups at the time the compound is added to thecoating composition, yet forms a polyaziridine in-situ. For example,compounds comprising a single aziridine group and a single(meth)acrylate group can form a dimer or oligomerize by reaction of the(meth)acrylate groups thereby forming a polyazirdine (i.e. diaziridine)compound.

In some favored embodiments, the composition comprises a compoundcomprising at least one (e.g. primary, secondary tertiary) amine groupand at least one organosilane (e.g. alkoxy silane) group. Such compoundscan improve bonding in combination with crosslinking certainfluoroelastomers.

In some embodiments, the amine curing agent may be characterized as anamino-substituted organosilane ester or ester equivalent that bear onthe silicon atom at least one, and preferably 2 or 3 ester or esterequivalent groups. Ester equivalents are known to those skilled in theart and include compounds such as silane amides (RNR′Si), silanealkanoates (RC(O)OSi), Si—O—Si, SiN(R)—Si, SiSR and RCONR′Si compoundsthat are thermally and/or catalytically displaceable by R″OH. R and R′are independently chosen and can include hydrogen, alkyl, arylalkyl,alkenyl, alkynyl, cycloalkyl, and substituted analogs such asalkoxyalkyl, aminoalkyl, and alkylaminoalkyl. R″ may be the same as Rand R′, except it may not be H. These ester equivalents may also becyclic such as those derived from ethylene glycol, ethanolamine,ethylenediamine (e.g. N-[3-(trimethoxylsilyl)propyl] ethylenediamine)and their amides.

Another such cyclic example of an ester equivalent is

In this cyclic example R′ is as defined in the preceding sentence,except that it may not be aryl. 3-aminopropyl alkoxysilanes are wellknown to cyclize upon heating, and these RNHSi compounds would be usefulin this invention. Preferably the amino-substituted organosilane esteror ester equivalent has ester groups such as methoxy that are easilyvolatilized as methanol. The amino-substituted organosilane must have atleast one ester equivalent; for example, it may be a trialkoxysilane.

For example, the amino-substituted organosilane may have the formula

(Z₂N-L-SiX′X″X′″), wherein

Z is hydrogen, alkyl, or substituted aryl or alkyl includingamino-substituted alkyl; and L is a divalent straight chain C1-12alkylene or may comprise a C3-8 cycloalkylene, 3-8 membered ringheterocycloalkylene, C2-12 alkenylene, C4-8 cycloalkenylene, 3-8membered ring heterocycloalkenylene or heteroarylene unit; and each ofX′, X″ and X′″ is a C1-18 alkyl, halogen, C1-8 alkoxy, C1-8alkylcarbonyloxy, or amino group, with the proviso that at least one ofX′, X″, and X′″ is a labile group. Further, any two or all of X′, X″ andX′″ may be joined through a covalent bond. The amino group may be analkylamino group.

L may be divalent aromatic or may be interrupted by one or more divalentaromatic groups or heteroatomic groups. The aromatic group may include aheteroaromatic. The heteroatom is preferably nitrogen, sulfur or oxygen.L is optionally substituted with C1-4 alkyl, C2-4 alkenyl, C2-4 alkynyl,C1-4 alkoxy, amino, C3-6 cycloalkyl, 3-6 membered heterocycloalkyl,monocyclic aryl, 5-6 membered ring heteroaryl, C1-4 alkylcarbonyloxy,C1-4 alkyloxycarbonyl, C1-4 alkylcarbonyl, formyl, C1-4alkylcarbonylamino, or C1-4 aminocarbonyl. L is further optionallyinterrupted by —O—, —S—, —N(Rc)-, —N(Rc)-C(O)—, —N(Rc)-C(O)—O—,—O—C(O)—N(Rc)-, —N(Rc)-C(O)—N(Rd)-, —O—C(O)—, —C(O)—O—, or —O—C(O)—O—.Each of Re and Rd, independently, is hydrogen, alkyl, alkenyl, alkynyl,alkoxyalkyl, aminoalkyl (primary, secondary or tertiary), or haloalkyl.

Examples of amino-substituted organosilanes include3-aminopropyltrimethoxysilane (SILQUEST A-1110),3-aminopropyltriethoxysilane (SILQUEST A-1100),bis(3-trimethoxysilylpropy)amine,bis(3-trimethoxysilylpropy)n-methylamine,3-(2-aminoethyl)aminopropyltrimethoxysilane (SILQUEST A-1120), SILQUESTA-1130, (aminoethylaminomethyl)phenethyltrimethoxysilane,(aminoethylaminomethyl)-phenethyltriethoxysilane,N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane (SILQUEST A-2120),bis-(.gamma.-triethoxysilylpropyl)amine (SILQUEST A-1170),N-(2-aminoethyl)-3-aminopropyltributoxysilane,6-(aminohexylaminopropyl)trimethoxysilane, 4-aminobutyltrimethoxysilane,4-aminobutyltriethoxysilane, p-(2-aminoethyl)phenyltrimethoxysilane,3-aminopropyltris(methoxyethoxyethoxy)silane,3-aminopropylmethyldiethoxy-silane, oligomeric aminosilanes such asDYNASYLAN 1146, 3-(N-methylamino)propyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropyltriethoxysilane,3-aminopropylmethyldiethoxysilane, 3-aminopropylmethyldimethoxysilane,3-aminopropyldimethylmethoxysilane, 3-aminopropyldimethylethoxysilane,and the following cyclic compounds:

A bis-silyl urea [RO)₃Si(CH₂)NR]₂C═O is another example of anamino-substituted organosilane ester or ester equivalent.

In some embodiments, the curing agent may comprise an amino group havinglatent functionality. One example of such curing agent is a blockedamine group, such as

R³—N═C(R¹)(R²)

wherein R¹ and R² are independently selected from a linear or branchedalkyl group comprising 1 to 6 carbon atoms. In typical embodiments R₁ ismethyl, and R² a linear or branched alkyl group comprising at least 2,3, 4, 5, or 6 carbon atoms. R³ is typically an organic group (e.g.having a molecular weight less than 500, 450, 400, 350, 300, or 250g/mole).

The blocked amine can be activated by moisture provided by wateradsorbed on the surface of the substrate being coated or from humidity.Deblocking begins in minutes and is generally complete within a few(e.g. two) hours. During deblocking the —N═C(R¹)(R²) group is convertedto —NH₂ that can then react with the (e.g. nitrile cure sites) of thefluoropolymer.

In some embodiments, the curing agent comprises a blocked amine groupand an alkoxy silane group. Such blocked amine curing agent can becharacterized by the following general formula:

(R⁴O)₃—Si—(CH₂)_(m)—N═C(R₁)(R₂)

wherein R¹ and R² are independently selected from a linear or branchedalkyl group comprising 1 to 6 carbon atoms as previously describedR¹ is independently selected from a linear or branched alkyl groupcomprising 1 to 6 carbon atoms, m is an integer from 1 to 4, and each R⁴is independently a C1 or C2 alkyl group.

One illustrative curing agent comprising a blocked amine group and analkoxy silane group isN-(1,3-dimethylbutylidene)aminopropyl-triethoxysilane, depicted asfollows:

Such curing agent is available from Gelest and from 3M as “3M™ Dynamer™Rubber Curative RC5125”.

In some embodiments, the amine curing agent comprises an aziridine groupand an alkoxy silane group. Such compounds are known for examples fromU.S. Pat. No. 3,243,429; incorporated herein by reference. Aziridinealkoxy silane compounds may have the general structure:

wherein R″ is hydrogen or a C1-C4 alkyl (e.g. methyl);X is a bond, a divalent atom, or a divalent linking group;n is 0, 1 or 2;m is 1, 2, or 3; andand the sum or n+m is 3.

One representative compound is 3-(2-methylaziridinyl)ethylcarboxylpropyltriethoxysilane.

Various other suitable aziridine crosslinkers are known, such asdescribed in WO2014/075246; published May 22, 2014, incorporated hereinby reference; and “NEW GENERATION OF MULTIFUNCTIONAL CROSSLINKERS,” (Seehttps://www.pstc.org/files/public/Milker00.pdf).

A single amine (e.g. curing agent) compound may be used or a combinationof amine (e.g. curing agent) compounds may be used. Thus, amine curingagent may be the sole curing agents. In this embodiment, the compositionis free of multi-olefinic crosslinkers including perfluoropolyethermulti-(meth)acrylate derivatives of “HFPO”, as described in US2006/0147723 (Jing, et al); incorporated herein by reference.Alternatively, the fluoropolymer composition may comprise suchmulti-olefinic crosslinkers including perfluoropolyethermulti-(meth)acrylate derivatives of “HFPO” in combination with the aminecuring agents(s) described herein.

The amount of amine (e.g. curing agent) is typically at least 0.01,0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, or0.5% by weight solids (i.e. excluding the solvent of the coatingcomposition). In some embodiments, the amount of amine (e.g. curingagent) compound is no greater than 5, 4.5, 4. 3.5, or 3% by weightsolids.

An appropriate level of curing agents can be selected by consideringcure properties, for example the time to develop maximum moving dierheometer (MDR) torque and minimum Mooney scorch of the curablecompositions. The optimum level will depend on the particularcombination of fluoropolymer and curing agents, and the desiredproperties of the cured elastomer.

In some embodiments, the fluoropolymer composition comprises an aminecuring agent in combination with an alkoxy silane compound that lacksamine functionality. In some embodiments, such alkoxy silanes may becharacterized as “non-functional” having the chemical formula:

R²Si(OR¹)_(m)

wherein R¹ is independently alkyl as previously described;R² is independently hydrogen, alkyl, aryl, alkaryl, or O R¹; andm ranges from 1 to 3, and is typically 2 or 3 as previously described.

Suitable alkoxy silanes of the formula R²Si(OR¹)_(m) include, but arenot limited to tetra-, tri- or dialkoxy silanes, and any combinations ormixtures thereof. Representative alkoxy silanes includepropyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane,butyltriethoxysilane, pentyltrimethoxysilane, pentyltriethoxysilane,heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane,octyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane,hexadecyltrimethoxysilane, hexadecyltriethoxysilane,octadecyltrimethoxysilane, octadecyltriethoxysilane,phenyltrimethoxysilane, phenyltriethoxysilane dimethyldimethoxysilaneand dimethyldiethoxysilane.

Preferably, the alkyl group(s) of the alkoxy silanes comprises from 1 to6, more preferably 1 to 4 carbon atoms. Preferred alkoxysilanes for useherein are selected from the group consisting of tetra methoxysilane,tetra ethoxysilane, methyl triethoxy silane, dimethyldiethoxysilane, andany mixtures thereof. A preferred alkoxysilane for use herein comprisestetraethoxysilane (TEOS). The alkoxy silane lacking organofunctionalgroups utilized in the method of making the coating composition may bepartially hydrolyzed, such as in the case of partially hydrolyzedtetramethoxysilane (TMOS) available from Mitsuibishi Chemical Companyunder the trade designation “MS-51”.

When present, the amount of alkoxy silane compound that lacksfunctionality (e.g. TESO) is typically at least 0.01, 0.02, 0.03, 0.04,0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, or 0.5% by weightsolids (i.e. excluding the solvent of the coating composition). In someembodiments, the amount of alkoxy silane compound that lacksfunctionality is no greater than 5, 4.5, 4. 3.5, or 3% by weight solids.

In some embodiments, an amine (e.g. curing agent) compound may be usedin combination with a non-amine curing agent.

When present, the amount of non-amine curing agent is typically at least0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3,0.4, or 0.5% by weight solids (i.e. excluding the solvent of the coatingcomposition). In some embodiments, the amount of non-amine curing agentis no greater than 5, 4.5, 4. 3.5, or 3% by weight solids.

In one embodiments, the non-amine curing agent is an alkoxy silane thatcomprises other functional groups, such as in the case of3-mercaptopropyl trimethoxysilane.

In other embodiments, the composition further comprises an organicperoxide, as a second curing agent. The peroxide will cause curing ofthe fluorinated polymer to form a cross-linked (cured) fluoropolymerwhen activated. Suitable organic peroxides are those which generate freeradicals at curing temperatures. Examples include dialkyl peroxides orbis(dialkyl peroxides), for example, a di-tertiarybutyl peroxide havinga tertiary carbon atom attached to the peroxy oxygen. Specific examplesinclude 2,5-dimethyl-2,5-di(tertiarybutylperoxy)hexyne-3 and2,5-dimethyl-2,5-di(tertiarybutylperoxy)hexane; dicumyl peroxide,dibenzoyl peroxide, tertiarybutyl perbenzoate,alpha,alpha′-bis(t-butylperoxy-diisopropylbenzene), anddi[1,3-dimethyl-3-(t-butylperoxy)-butyl]carbonate. Generally, about 1 to5 parts of peroxide per 100 parts of fluoropolymer may be used.

The curing agents may also be present on carriers, for example silicacontaining carriers. A peroxide cure system may also include in additionone or more coagent. Typically, the coagent includes a polyunsaturatedcompound which is capable of cooperating with the peroxide to provide auseful cure. These coagents may typically be added in an amount between0.1 and 10 parts per hundred parts fluoropolymer, preferably between 2and 5 parts per hundred parts fluoropolymer. Examples of useful coagentsinclude triallyl cyanurate; triallyl isocyanurate; triallyltrimellitate; tri(methylallyl)isocyanurate;tris(diallylamine)-s-triazine; triallyl phosphite; (N,N′)-diallylacrylamide; hexaallyl phosphoramide; (N,N,N,N)-tetraalkyltetraphthalamide; (N,N,N′,N-tetraallylmalonamide; trivinyl isocyanurate;2,4,6-trivinyl methyltrisiloxane; N,N′-m-phenylenebismaleimide;diallyl-phthalate and tri(5-norbornene-2-methylene)cyanurate.Particularly useful is triallyl isocyanurate.

In some embodiments, the fluoropolymer composition may also be curedusing actinic irradiation, for example but not limited to e-beam curing,allowing for dual cure systems.

The fluoropolymer (coating solution) compositions comprises at least onesolvent. The solvent is capable of dissolving the fluoropolymer. Thesolvent is typically present in an amount of at least 25% by weightbased on the total weight of the coating solution composition. In someembodiments, the solvent is present in an amount of at least 30, 35, 40,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95% or greater based on thetotal weight of the coating solution composition.

The fluoropolymer (coating solution) composition typically comprises atleast 0.01, 0.02, 0.03, 0.03, 0.04, 0.04, 0.05, 0.06, 0.7, 0.8. 0.9 or1% by weight of fluoropolymer, based on the weight of the total coatingsolution composition. In some embodiments, the fluoropolymer coatingsolution composition comprises at least 2, 3, 4, or 5% by weight offluoropolymer. In some embodiments, the fluoropolymer coating solutioncomposition comprises at least 6, 7, 8, 9 or 10% by weight offluoropolymer. The fluoropolymer coating solution composition typicallycomprises no greater than 50, 45, 40, 35, 30, 25, or 20% by weight offluoropolymer, based on the weight of the total coating solutioncomposition.

Optimum amounts of solvent and fluoropolymers may depend on the finalapplication and may vary. For example, to provide thin coatings, verydilute solutions of fluoropolymer in the solvent may be desired, forexample amounts of from 0.01% by weight to 5% by weight offluoropolymer. Also for application by spray coating composition of lowviscosity may be preferred over solutions with high viscosity. Theconcentration of fluoropolymer in the solution affects the viscosity andmay be adjusted accordingly. An advantage of the present disclosure isthat also solutions with high concentrations of fluoropolymer can beprepared that still provide clear liquid composition of low viscosity.

In some embodiments, the fluoropolymer coating solution compositions maybe liquids. The liquids may have, for example, a viscosity of less than2,000 mPas at room temperature (20° C.+/−2° C.). In other embodiments,the fluoropolymer coating solution compositions are pastes. The pastesmay have, for example, a viscosity of from 2,000 to 100.000 mPas at roomtemperature (20° C.+/−2° C.).

The solvent is a liquid at ambient conditions and typically has aboiling point of greater than 50° C. Preferably, the solvent has aboiling point below 200° C. so that it can be easily removed. In someembodiments, the solvent has a boiling point below 190, 180, 170, 160,150, 140, 130, 120, 110, or 100° C.

The solvent is partially fluorinated or perfluorinated. Variouspartially fluorinated or perfluorinated solvents are known includingperfluorocarbons (PFCs), hydrochlorofluorocarbons (HCFCs),perfluoropolyethers (PFPEs), and hydrofluorocarbons (HFCs), as well asfluorinated ketones and fluorinated alkyl amines.

In some embodiments, the solvent has a global warming potential (GWP,100 year ITH) of less than 1000, 900, 800, 700, 600, 500, 400, 300, 200or 100. The GWP is typically greater than 0 and may be at least 10, 20,30, 40, 50, 60, 70, or 80.

As used herein, GWP is a relative measure of the global warmingpotential of a compound based on the structure of the compound. The GWPof a compound, as defined by the Intergovernmental Panel on ClimateChange (IPCC) in 1990 and updated in subsequent reports, is calculatedas the warming due to the release of 1 kilogram of a compound relativeto the warming due to the release of 1 kilogram of CO₂ over a specifiedintegration time horizon (ITH).

${GWP}_{x} = \frac{\int_{0}^{ITH}{F_{x}C_{xo}{\exp\left( {{- t}/\tau_{x}} \right)}\;{dt}}}{\int_{0}^{ITH}{F_{{{CO}\;}_{2}}{C_{{{CO}\;}_{2}}(t)}\;{dt}}}$

where F is the radiative forcing per unit mass of a compound (the changein the flux of radiation through the atmosphere due to the IR absorbanceof that compound), C_(o) is the atmospheric concentration of a compoundat initial time, τ is the atmospheric lifetime of a compound, t is time,and x is the compound of interest.

In some embodiments, the solvent comprises a partially fluorinated etheror a partially fluorinated polyether. The partially fluorinated ether orpolyether may be linear, cyclic or branched. Preferably, it is branched.Preferably it comprises a non-fluorinated alkyl group and aperfluorinated alkyl group and more preferably, the perfluorinated alkylgroup is branched.

In one embodiment, the partially fluorinated ether or polyether solventcorresponds to the formula:

Rf—O—R

wherein Rf is a perfluorinated or partially fluorinated alkyl or(poly)ether group and R is a non-fluorinated or partially fluorinatedalkyl group. Typically, Rf may have from 1 to 12 carbon atoms. Rf may bea primary, secondary or tertiary fluorinated or perfluorinated alkylresidue. This means, when Rf is a primary alkyl residue the carbon atomlinked to the ether atoms contains two fluorine atoms and is bonded toanother carbon atom of the fluorinated or perfluorinated alkyl chain. Insuch case Rf would correspond to R_(f) ¹—CF₂— and the polyether can bedescribed by the general formula:

R_(f) ¹—CF₂—O—R.

When Rf is a secondary alkyl residue, the carbon atom linked to theether atom is also linked to one fluorine atoms and to two carbon atomsof partially and/or perfluorinated alkyl chains and Rf corresponds to(R_(f) ²R_(f) ³)CF—. The polyether would correspond to (R_(f) ²R_(f)³)CF—O—R.

When R_(f) is a tertiary alkyl residue the carbon atom linked to theether atom is also linked to three carbon atoms of three partiallyand/or perfluorinated alkyl chains and Rf corresponds to (R_(f) ⁴R_(f)⁵R_(f) ⁶)—C—. The polyether then corresponds to (R_(f) ⁴R_(f) ⁵R_(f)⁶)—C—OR. R_(f) ¹; R_(f) ²; R_(f) ³; R_(f) ⁴; R_(f) ⁵; R_(f) ⁶ correspondto the definition of Rf and are a perfluorinated or partiallyfluorinated alkyl group that may be interrupted once or more than onceby an ether oxygen. They may be linear or branched or cyclic. Also acombination of polyethers may be used and also a combination of primary,secondary and/or tertiary alkyl residues may be used.

An example of a solvent comprising a partially fluorinated alkyl groupincludes C₃F₇OCHFCF₃ (CAS No. 3330-15-2).

An example of a solvent wherein Rf comprises a perfluorinated(poly)ether is C₃F₇OCF(CF₃)CF₂OCHFCF₃ (CAS No. 3330-14-1).

In some embodiments, the partially fluorinated ether solvent correspondsto the formula:

CpF2p+1-O-CqH2q+1

wherein q is an integer from 1 to and 5, for example 1, 2, 3, 4 or 5,and p is an integer from 5 to 11, for example 5, 6, 7, 8, 9, 10 or 11.Preferably, C_(p)F_(2p+1) is branched. Preferably, C_(p)F_(2p+1) isbranched and q is 1, 2 or 3.

Representative solvents include for example1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane and3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluroro-2-(trifluoromethyl)hexane.Such solvents are commercially available, for example, under the tradedesignation NOVEC from 3M Company, St. Paul, Minn.

The fluorinated (e.g. ethers and polyethers) solvents may be used aloneor in combination with other solvents, which may be fluorochemicalsolvents or non-fluorochemical solvents. When a non-fluorochemicalsolvent is combined with a fluorinated solvent, the concentrationnon-fluorochemical solvent is typically less than 30, 25, 20, 15, 10 or5 wt-% with respect to the total amount of solvent. Representativenon-fluorochemical solvents include ketones such as acetone, MEK, methylisobutyl ketone, methyl amyl ketone and NMP; ethers such astetrahydrofuran, 2-methyl tetrahydrofuran and methyl tetrahydrofurfurylether; esters such as methyl acetate, ethyl acetate and butyl acetate;cyclic esters such as delta-valerolactone and gamma-valerolactone.

Compositions containing curable fluoroelastomers may further containadditives as known in the art. Examples include acid acceptors. Suchacid acceptors can be inorganic or blends of inorganic and organic acidacceptors. Examples of inorganic acceptors include magnesium oxide, leadoxide, calcium oxide, calcium hydroxide, dibasic lead phosphate, zincoxide, barium carbonate, strontium hydroxide, calcium carbonate,hydrotalcite, etc. Organic acceptors include epoxies, sodium stearate,and magnesium oxalate. Particularly suitable acid acceptors includemagnesium oxide and zinc oxide. Blends of acid acceptors may be used aswell. The amount of acid acceptor will generally depend on the nature ofthe acid acceptor used. Typically, the amount of acid acceptor used isbetween 0.5 and 5 parts per 100 parts of fluorinated polymer.

The fluoropolymer composition may contain further additives, such asstabilizers, surfactants, ultraviolet (“UV”) absorbers, antioxidants,plasticizers, lubricants, fillers, and processing aids typicallyutilized in fluoropolymer processing or compounding, provided they haveadequate stability for the intended service conditions. A particularexample of additives includes carbon particles, like carbon black,graphite, soot. Further additives include but are not limited topigments, for example iron oxides, titanium dioxides. Other additivesinclude but are not limited to clay, silicon dioxide, barium sulphate,silica, glass fibers, or other additives known and used in the art.

The fluoropolymer compositions may be prepared by mixing the polymer,the curing agent(s) including at least one amine curing agent, optionaladditives and the fluorinated solvent. In some embodiments, thefluoropolymer is first dissolved in the fluorinated solvent and theother additives, including the curing agent(s) are added thereafter.

The coating composition described herein including fluorinated solventis “stable, meaning that the coating composition remains homogeneouswhen stored for at least 24 hours at room temperature in a sealedcontainer. In some embodiments, the coating composition is stable forone week or more. “Homogeneous” refers to a coating composition thatdoes not exhibit a visibly separate precipitate or visibly separatelayer when freshly shaken, placed in a 100 ml glass container andallowed to stand at room temperature for at least 4 hours.

In some embodiments, the fluoropolymer is first combined with othersolid ingredients and in particular with the amine(s) described herein.The fluoropolymer and amine compounds can be combined in conventionalrubber processing equipment to provide a solid mixture, i.e. a solidpolymer containing the additional ingredients, also referred to in theart as a “compound”. Typical equipment includes rubber mills, internalmixers, such as Banbury mixers, and mixing extruders. During mixing thecomponents and additives (including the amine curing agent) aredistributed uniformly throughout the resulting fluorinated polymer“compound” or polymer sheets. The compound is then preferablycomminuted, for example by cutting it into smaller pieces and is thendissolved in the solvent.

The fluoropolymer coating solution compositions provided herein aresuitable for coating substrates. The fluoropolymer coating solutioncompositions may be formulated to have different viscosities dependingon solvent and fluoropolymer content and the presence or absence ofoptional additives. The fluoropolymer coating solution compositionstypically contain or are solutions of fluoropolymers and may be in theform of liquids or pastes. Nevertheless, the compositions may containdispersed or suspended materials but these materials preferably areadditives and not fluoropolymers of the type as described herein.Preferably, the compositions are liquids and more preferably they aresolutions containing one or more fluoropolymer as described hereindissolved in a solvent as described herein.

The fluoropolymer compositions provided herein are suitable for coatingsubstrates and may be adjusted (by the solvent content) to a viscosityto allow application by different coating methods, including, but notlimited to spray coating or printing (for example but not limited toink-printing, 3D-printing, screen printing), painting, impregnating,roller coating, bar coating, dip coating and solvent casting.

Coated substrates and articles may be prepared by applying thefluoropolymer compositions to a substrate and removing the solvent. Thecuring may occur to, during, or after removing the solvent. The solventmay be reduced or completely removed, for example for evaporation,drying or by boiling it off. After removal of the solvent thecomposition may be characterized as “dried”.

Curing may be achieved by the conditions suitable for the curing systemand cure sites used. Depending on the cure sites and curing system usedcuring may be achieved by heat-treating the curable fluoroelastomercomposition or at room temperature, or by irradiation, for exampleUV-curing or actinic irradiation, for example e-beam curing. Thefluoropolymer composition, substrate, or both are transmissive to thecuring radiation. In some embodiments, a combination of UV curing andthermal (e.g. post) curing is utilized. The curing is carried out at aneffective temperature and effective time to create a curedfluoroelastomer. Optimum conditions can be tested by examining thefluoroelastomer for its mechanical and physical properties. Curing maybe carried out under pressure or without pressure in an oven. A postcuring cycle at increased temperatures and or pressure may be applied toensure the curing process is fully completed. The curing conditionsdepend on the curing system used.

In some embodiments, the composition comprises at least onefluoropolymer comprising one or more halogenated cure sites (i.e.iodine, bromine, chlorine) and an amine curing agent. The composition iscured by UV-curing.

Without intending to be bound by theory, it is surmised that the aminecuring agent functions as an electron donor and the halogenated curesites function as an electron acceptor. Thus, the amine curing agentalone can initiate UV-curing in the absence of free-radicalphotoinitiators. Although, conventional free-radical initiators are notrequired, the composition can optionally further comprisephotoinitiator. Useful photoinitiators include benzoin ethers such asbenzoin methyl ether and benzoin isopropyl ether; substitutedacetophenones; substituted α-ketols such as 2-methyl-2-hydroxypropiophenone; aromatic sulfonyl chlorides such as2-naphthalene-sulfonyl chloride; and photoactive oximes such as1-phenyl-1,2-propanedione-2-(0-ethoxy-carbonyl)oxime.

In some embodiments, the UV radiation may have sufficient intensity at awavelength of at least 190, 200, 205 or 210 nm. In some embodiments, theUV radiation may have sufficient intensity at a wavelength no greaterthan 700, 600, 500, 400 or 300 nm. In some embodiments, the UV radiationmay have sufficient intensity at a wavelength ranging from 270-280 nmsuch that in the presence of an (e.g. amine) electron donor awavelength-induced single electron transfer reaction may occur betweenC—I bonds. In some embodiments, the UV radiation may have sufficientintensity at a wavelength ranging below 240 nm (e.g. 150-200 nm) suchthat in the presence of an (e.g. amine) electron donor awavelength-induced single electron transfer reaction may occur betweenC—Cl or C—Br bonds.

UV light sources can be of various types. Low light intensity sources,such as blacklights, generally provide intensities ranging from 0.1 or0.5 mW/cm² (millwatts per square centimeter) to mW/cm² (as measured inaccordance with procedures approved by the United States NationalInstitute of Standards and Technology as, for example, with a UVIMAP UM365 L-S radiometer manufactured by Electronic Instrumentation &Technology, Inc., in Sterling, Va.). High light intensity sourcesgenerally provide intensities greater than 10, 15, or 20 mW/cm² rangingup to 450 mW/cm² or greater. In some embodiments, high intensity lightsources provide intensities up to 500, 600, 700, 800, 900 or 1000mW/cm². UV light to polymerize the ethylenically unsaturated monomer(s)can be provided by various light sources such as light emitting diodes(UEDs), fluorescent blacklights, arc-lamps such as xenon-arc lamps andmedium and low pressure mercury lamps (including germicidal lamps),microwave-driven lamps, lasers etc. or a combination thereof. Thecomposition can also be polymerized with higher intensity light sourcesas available from Fusion UV Systems Inc. Lamps that emit ultraviolet orblue light are typically preferred. The UV exposure time forpolymerization and curing can vary depending on the intensity of thelight source(s) used. For example, complete curing with a low intensitylight course can be accomplished with an exposure time ranging fromabout 30 to 300 seconds; whereas complete curing with a high intensitylight source can be accomplished with shorter exposure time ranging fromabout 5 to 20 seconds. Partial curing with a high intensity light sourcecan typically be accomplished with exposure times ranging from about 2seconds to about 5 or 10 seconds. In some embodiments, post curing maybe carried out at a temperature between 170° C. and 250° C. for a periodof 0.1 to 24 hours.

In some embodiments, post curing may be carried out at lowertemperatures. Post curing at lower temperatures is amenable for coatingheat sensitive substrates. In some embodiments, the post curing occursat a temperature ranging from 100, 110, 120, 130, 135 or 140° C. up to170° C. for a period of 5-10 minutes to 24 hours. In some embodiments,the temperature is no greater than 169, 168, 167, 166, 165, 164, 163,162, 161, or 160° C. In some embodiments, the temperature is no greaterthan 135, 130, 125, or 120° C.

In favored embodiments, after curing the fluoropolymer is sufficientlycrosslinked such that at least 80, 85, 90 wt. % or greater cannot bedissolved in fluorinated solvent (e.g. HFE7500) at a weight ratio of 5grams of fluoropolymer in 95% by weight of fluorinated solvent.

The compositions may be used for impregnating substrates, printing onsubstrates (for example screen printing), or coating substrates, forexample but not limited to spray coating, painting dip coating, rollercoating, bar coating, solvent casting, paste coating. Suitablesubstrates may include any solid surface and may include substrateselected from glass, plastics (e.g. polycarbonate), composites, metals(stainless steel, aluminum, carbon steel), metal alloys, wood, paperamong others. The coating may be coloured in case the compositionscontains pigments, for example titanium dioxides or black fillers likegraphite or soot, or it may be colorless in case pigments or blackfillers are absent.

Bonding agents and primers may be used to pretreat the surface of thesubstrate before coating. For example, bonding of the coating to metalsurfaces may be improved by applying a bonding agent or primer. Examplesinclude commercial primers or bonding agents, for example thosecommercially available under the trade designation CHEMLOK. Articlescontaining a coating from the compositions provided herein include butare not limited to impregnated textiles, for example protectiveclothing. Textiles may include woven or non-woven fabrics. Otherarticles include articles exposed to corrosive environments, for exampleseals and components of seals and valves used in chemical processing,for example but not limited to components or linings of chemicalreactors, molds, chemical processing equipment for example for etching,or valves, pumps and tubings, in particular for corrosive substances orhydrocarbon fuels or solvents; combustion engines, electrodes, fueltransportation, containers for acids and bases and transportationsystems for acids and bases, electrical cells, fuel cells, electrolysiscells and articles used in or for etching.

An advantage of the coating compositions described herein is that thecoating compositions can be used to prepare coatings of high or lowthickness. In some embodiments, the dried and cured coating has athickness of 0.1 microns to 1 or 2 mils. In some embodiments, the driedand cured coating thickness is at least 0.2, 0.3, 0.4, 0.5, or 0.6microns. In some embodiments, the dried and cured coating thickness isat least 1, 2, 3, 4, 5, or 6 microns.

The dried and cured coating can exhibit good adhesion to varioussubstrates (e.g. glass, polycarbonate,), as evidence by the coatingexhibiting a 2, and preferably a 3 or 4 according to the Boiling WaterTest described in the examples. In favored embodiments, the dried andcured coating is durable as evidence by the coating exhibiting a 2, andpreferably a 3 or 4 according to the Abrasion Test described in theexamples. In some embodiments, the coating is durable, according to theAbrasion Test after being subjected to the Boiling Water Test.

In some embodiments, the dried and cured coating has good hydrophobicand oleiphobic properties according to the Black Permanent MarkerResistance Test, i.e. the marker fluid beads and is easy to remove witha paper towel or cloth. In some embodiments, the dried and cured coatinghas good hydrophobic and oleiphobic properties, as determined by ContactAngle Measurements (as determined according to the test method describedin the examples). In some embodiments, the advancing and/or recedingcontact angle with water can be at least 100, 105, 110, 115, 120, 125 or130 degrees. In some embodiments, the advancing and/or receding contactangle with hexadecane can be at least 60, 65, 70, or 75 degrees. In someembodiments, the coating exhibits such contact angles, after beingsubjected to the Boiling Water Test or after being subject the BoilingWater Test and the Abrasion Test (as determined according to the testmethod described in the examples).

In some embodiments, the dried and cured coating exhibits good corrosionresistance (i.e. not corroded) according to the Acid/Base Corrosion Testdescribed in the examples.

As used herein the term “partially fluorinated alkyl” means an alkylgroup of which some but not all hydrogens bonded to the carbon chainhave been replaced by fluorine. For example, an F₂HC—, or an FH₂C— groupis a partially fluorinated methyl group. Alkyl groups where theremaining hydrogen atoms have been partially or completely replaced byother atoms, for example other halogen atoms like chlorine, iodineand/or bromine are also encompassed by the term “partially fluorinatedalkyl” as long as at least one hydrogen has been replaced by a fluorine.For example, residues of the formula F₂ClC—OCF₃ or FHClC—O—CF₃ are alsopartially fluorinated alkyl residues.

A “partially fluorinated ether” is an ether containing at least onepartially fluorinated group, or an ether that contains one or moreperfluorinated groups and at least one non-fluorinated or at least onepartially fluorinated group. For example, F₂HCO—CH₃, F₃C—O—CH₃,F₂HC—O—CFH₂, and F₂HC—O—CF₃ are examples of partially fluorinatedethers. Ethers groups where the remaining hydrogen atoms have beenpartially or completely replaced by other atoms, for example otherhalogen atoms like chlorine, iodine and/or bromine are also encompassedby the term “partially fluorinated alkyl” as long as at least onehydrogen has been replaced by a fluorine. For example, ethers of theformula F₂ClC—O—CF₃ or FHClC—O—CF₃ are also partially fluorinatedethers.

The term “perfluorinated alkyl” or “perfluoro alkyl” is used herein todescribe an alkyl group where all hydrogen atoms bonded to the alkylchain have been replaced by fluorine atoms. For example, F₃C— representsa perfluoromethyl group.

A “perfluorinated ether” is an ether of which all hydrogen atoms havebeen replaced by fluorine atoms. An example of a perfluorinated ether isF₃C—O—CF₃.

The following examples are provided to further illustrate the presentdisclosure without any intention to limit the disclosure to the specificexamples and embodiments provided.

TABLE 1 Materials: Abbreviation Description Source PFE-131Nitrile-containing perfluoroelastomer 3M Dyneon, St. Paul, MN PFE-40Iodo-containing perfluoroelastomer 3M Dyneon PFE-60 Bromo-containingperfluoroelastomer 3M Dyneon Novec 7500 Fluorinated ether solvent 3MCompany, St. Paul, (HFE-7500) MN PZ Polyaziridine commercially availableas DSM Coating Resins, the trade designation “CX-100” LLC DBU1,8-diazabicyclo [5.4.01 undec-7-ene Alfa AEsar APMS(3-Aminopropyl)trimethoxy silane Sigma-Aldrich APES/APS(3-Aminopropyl)triethoxysilane Aldrich N-ME-APMS N-methylaminopropyltrimethoxysilane Gelest Corporation BTMPABis(3-trimethoxysilylpropyl)amine Gelest Corporation, Morrisville, PABTMP-ME-A Bis(3-trimethoxysilylpropyl)-n- Gelest Corporation methylamineTMP-ETDA N-[3-(Trimethoxylsilyl)propyl] Gelest Corporationethylenediamine Ethylene diamine Sigma-Aldrich 3M ™ Dynamer ™N-(1,3-dimethylbutylidene)-3- 3M, St. Paul, MN Rubber Curative(triethoxysilyl)-1-propaneamine RC5125 (RC5125) Alkoxysilyl aziridine2-(2-methylzairidinyl) Prepared as described in (SA)ethylcarboxylpropyltriethoxysilane WO2015/066868 DMAPSN-dimethylaminopropyl silane TEOS Tetraethoxysilane Sigma-Aldrich, St.Louis, MO TMOS Tetramethyl orthosilicate Sigma-Aldrich MPS3-mercaptopropyl trimethoxy silane Sigma-Aldrich Darocur 11732-hydroxyl-2-methylpropiophenone Sigma-Aldrich Soda-lime float glassCleaned with Alconox detergent (North Cardinal Glass Industriessubstrate White Plains, NY, available through (Eden Prairie, MinnesotaSigma-Aldrich,) water washed and IPA USA). rinsed before use. AluminumSubstrate Cleaned by soaking in acetone/IPA for LOFTech, St.Paul, MN andwiped dry Carbon Steel Substrate 1 × 3 × 0.1″ or 3 × 6 × 0.1″ Cleaned byLOFTech, St.Paul, MN abrading with 3M Company grade 320 sandpaper andsubsequently rinsed with water and isopropyl alcohol (IPA). StainlessSteel 1 × 3 × 0.1″ or 3 × 6 × 0.1″ Cleaned by LOFTech, St.Paul, MNSubstrate abrading with 3M Company grade 320 sandpaper and subsequentlyrinsed with water and isopropyl alcohol (IPA). Polycarbonate Substrate 4mil thick GE Advanced Materials Speciality film and sheet, Pittsfield,Mass. PET Film Clear PET film with primer on both sides Mitsubishi

Perfluoroelastomer Coating Solution Preparation:

Perfluoroelastomer (e.g. PFE131, PFE40, PFE60) gum was cut into piecesand dissolved in HFE-7500 solvent by constantly shaking or stirring thesolution overnight to obtain a 5 or 10 wt % perfluoroelastomer (PFE131)in HFE-7500 solution. To the perfluoroelastomer solution was added theindicated amine (e.g. curing agent) compound, at the amounts describedin the Tables below. Some of the coating solutions also contained TEOSas indicated in the Tables below. The coating solutions were stirredunder vortex for 1-2 min at 2500 RPM or shaken, until the coating washomogeneous.

Crosslinking Test:

To the 5 wt % perfluoroelastomer (PFE131) in HFE-7500 solution was addedthe indicated amine curing agent(s) at the amounts described in Table 2.The solutions were well mixed and 3-5 mL of each coating solution wastransferred into an aluminum foil dish using a plastic pipette. Thesolutions were dried and cured for 10 minutes in an oven at thetemperature described in the Tables. Each of the resulting dried andcured coatings were removed from the dish and placed in HFE-7500separately. The solutions were stirred overnight to determine if thedried and cured coating dissolved in the HFE-7500 solvent. Dried andcured coatings that were not soluble in the solvent were considered tobe crosslinked (Y=Yes (i.e. crosslinked), N=No).

TABLE 2 Crosslinking Test Results of Dried & Cured Coatings Preparedfrom 5 wt % PFE131 in HFE-7500 and Amine Curing Agent Curing Agent, Wt %Solids 100° C. 120° C. 140° C. 175° C. Ex. 2-1 - APMS, 2 wt % NT Y Y NTEx. 2-2 - PZ, 2 wt % NT Y Y NT Ex. 2-3 - DBU, 2 wt % NT Y Y NT Ex 2-4 -Alkoxysilyl NT Y Y NT aziridine (SA), 2 wt % Ex. 2-5 - RC5125, 3 wt % NTY Y NT Ex. 2-6 - BTMPA, 3 wt % NT Y Y NT Ex. 2-7 - MPS/DMAPS = NT Y Y Y9/1 wt ratio, 5 wt % Ex. 2-8 - DMAPS, 2 wt % NT Y Y Y Ex. 2-9 - RC5125 -3 wt %/ Y Y Y Y TEOS, 1.5 wt % Ex. 2-10 - BTMPA- 3 wt %/ Y Y Y Y TEOS1.5 wt % NT—Not TestedCoating the Perfluoroelastomer Coating Solution onto a Glass Substrate

The coating solutions were applied with a No. 12 Meyer rod to the glasssubstrate (described in Table 1). Unless specified otherwise, thecoatings were dried and cured for 10 minutes at the temperaturespecified in the Tables. The 5 wt-% solutions provided a dried and curedcoating thickness of 1-3 microns. The 10 wt-% solutions provided a driedand cured coating thickness of 2-6 microns. The 1 wt-% solutionsprovided a dried and cured coating thickness of 0.2-0.6 microns. Thecoated substrate was evaluated with the following tests.

Coating Solution Shelf-Life:

Coating solution shelf-life was determined by the coating solutionflowability. The time from solution preparation until the solutionbecame non-flowable was defined as the shelf-life.

Bonding Evaluation:

The bonding of the dried and cured coating to the substrate wasevaluated according to the following criteria.

0—Coating boiled off

1—Coating peels off easily

2—Coating peels off with moderate force

3—Coating peels off with greater force

4—Coating breaks upon peeling

Boiling Water Test:

The coated glass substrate having the dried and cured coating wassubmerged in a beaker of boiling water for 2 hours. After boiling, thebonding was evaluated as described above.

Abrasion Testing:

A TABER 5900 liner abrader (obtained from Taber Industries of NorthTonawanda, N.Y.) fitted with a 2.5 cm button covered with aKIMBERLY-CLARK L-30 WYPALL towel (obtained from Kimberly Clark ofRoswell, Ga.) and a 5.1 cm×5.1 cm crock cloth (obtained from TaberIndustries, North Tonawanda, N.Y.). The samples were abraded for 200 to500 cycles at a rate of cycles/minute (1 cycle consisted of a forwardwipe followed by a backward wipe) with a load of 1000 grams followingASTM D0460 and a stroke length of 5.1 cm.

Abrasion Testing was conducted on coated substrates before and after thecoated substrate was subjected to the Boiling Water Test. After AbrasionTesting the coated sample was evaluated according to the followingcriteria:

0—Coating is completely abraded off

1—Coating is partially abraded off

2—Coating is slightly abraded off, visible abrasion mark on coating

3—Coating is not abraded off, visible abrasion mark on coating

4—Coating is not abraded off, very faint abrasion mark on coating

Black Permanent Marker Resistance Test:

A 3-5 mm wide straight line was drawn on the dried and cured coating ofthe coated substrate using a black Sharper™ permanent marker with thehelp of a ruler at a speed of roughly 6 inches per second (0.15 m/s). Ifthe marker fluid on the dried and cured coating beads and is easy toremove with a paper towel or a cloth, the coating surface was consideredto have “Good” hydrophobic and oleophobic. In contrast, if the mark lefton the coating surface is a solid line, and difficult to remove with apaper towel or a cloth, such a surface was not considered to be anoleophobic surface.

Contact Angle Measurement:

Contact angle measurements were made on the dried and cured coating ofthe coated glass substrate before and after subjecting the sample toAbrasion Testing. The Abrasion Testing was conducted on samples beforeand after being subjected to the Boiling Water Test. The resultingcoatings were rinsed for 1 minute by hand agitation in isopropanolalcohol before being subjected to measurement of water and hexadecanecontact angles. Measurements were made using as-received reagent-gradehexadecane (Sigma-Aldrich) and deionized water filtered through afiltration system obtained from Millipore Corporation (Billerica,Mass.), on a video contact angle analyzer available as product numberVCA-2500XE from AST Products (Billerica, Mass.). Reported values werethe averages of measurements on at least three drops measured on theright and the left sides of the drops, and are shown in the Tables. Dropvolumes were 5 microliters for static measurements and 1-3 microlitersfor advancing and receding contact angles. For hexadecane, onlyadvancing and receding contact angles are reported because the staticand advancing values were found to be nearly equal.

TABLE 3 Test Results of Dried & Cured Coatings Prepared from 5 wt %PFE131 and RC5125 Amine Curing Agent in HFE on Glass Substrate Cured at140° C. Abrasion Test Black (200 cycles) Permanent Boiling Before inAfter in Marker Cross- Coating Wt % Solids RC5125, Water boiling boilingResistance linking Solution Wt % solids TEOS Test water water Test TestShelf-life Ex. 3-1 - Comparative 0 1 NT Good No 24+ hrs PFE131/no RC5125Ex. 3-2 - 0.25 wt % 1 1 NT Good NT 6 hrs Ex. 3-3 - 0.5 wt % 1 2 2 GoodYes 5 hrs Ex. 3-4 - 1 wt % 1 2 3 Good NT NT Ex. 3-5 - 1.5 wt % 2 4 4Good Yes 53 hrs Ex. 3-6 - 1.5 wt %, 2 4 4 Good Yes 53 hrs 1.5 wt % TEOSEx. 3-7 - 1.5 wt %, 2 3 NT Good Yes NT 3 wt % TEOS Ex. 3-8 - 3 wt % 3 44 Good Yes 29 hrs Ex. 3-9 - 3 wt %, 3 4 4 Good Yes 32 hrs 1.5 wt % TEOSEx. 3-10 - 5 wt % 3 4 2 Good Yes <10 hrs Ex. 3-11 - 5 wt %, 3 4 4 GoodYes <10 hrs 1.5 wt % TEOS NT—Not Tested

TABLE 4 Test Results of Dried & Cured Coatings Prepared from 5 wt %PFE131 and BTMPA Amine Curing Agent in HFE on Glass Substrate at 140° C.Abrasion Test Black (200 cycles) Permanent Boiling Before in After inMarker Cross- Coating Wt % Solids BTMPA, Water boiling boilingResistance linking Solution Wt % solid TEOS Test water water Test TestShelf-life Ex. 4-1 - 0.5 wt % 1 NT NT Good NT 24+ hrs Ex. 4-2 - 1 wt % 1NT NT Good NT 24+ hrs Ex. 4-3 - 1.5 wt % 2 4 4 Good Yes 70 hrs Ex. 4-4 -1.5 wt %, 2 4 4 Good Yes 70 hrs 1.5 wt % TEOS Ex. 4-5 - 3 wt % 4 4 4Good Yes 30 hrs Ex. 4-6 - 3 wt %, 4 4 4 Good Yes 33 hrs 1.5 wt % TEOSEx. 4-7 - 5 wt % 4 4 4 Good Yes 10 hrs NT—Not Tested

TABLE 5 Test Results of Dried & Cured Coatings Prepared from 5 wt %PFE131 and RC5125 or BTMPA Amine Curing Agent in HFE on Glass PlateSubstrate at 160° C. Abrasion Test Black (200 cycles) Permanent Wt %Solids Amine Boiling Before in After in Marker Cross- Coating CuringAgent, Water boiling boiling Resistance linking Solution Wt % solidsTEOS Test water water Test Test Shelf-life Ex. 5-1 - 1 wt % 1 3 NT GoodYes NT RC5125, 1 wt % TEOS Ex. 5-2 - 1.5 wt % 2 3 NT Good Yes 53 hrsRC5125, 1.5 wt % TEOS Ex. 5-3 - 3 wt % BTMPA 4 4 4 Good Yes 30 hrs Ex.5-4 - 3 wt % BTMPA, 4 4 4 Good Yes 33 hrs 1.5 wt % TEOS NT—Not Tested

TABLE 6 Test Results of Dried & Cured Coatings Prepared from 5 wt %PFE131 and RC5125 or APMS Amine Curing Agent in HFE on Glass Substrateat 175° C. Abrasion Test Black (200 cycles) Permanent Wt % Solids AmineBoiling Before in After in Marker Cross- Coating Curing Agent, Waterboiling boiling Resistance linking Solution Wt % solids TEOS Test waterwater Test Test Shelf-life Ex. 6-1 - Comparative 0 NT NT Good No 24+ hrsPFE131 Ex. 6-2 - 0.25 wt % RC5125 1 2 NT Good Yes 6 hrs Ex. 6-3 - 0.5 wt% RC5125 1 2 NT Good Yes <6 hrs Ex. 6-4 - 1 wt % RC5125 1 3 NT Good YesNT Ex. 6-5 - 1.5 wt % RC5125 2 4 NT Good Yes 53 hrs Ex. 6-6 - 1 wt %RC5125, 1 4 NT Good Yes NT 1 wt % TEOS Ex. 6-7 - 1.5 wt % RC5125, 2 3 NTGood Yes 53 hrs 1.5 wt % TEOS Ex. 6-8 - 1.5 wt % APMS 3 4 NT Good Yes <2hrs NT = Not Tested

TABLE 7 Test Results of Dried & Cured Coatings Prepared from 5 wt %PFE131 and RC5125 or BTMPA Amine Curing Agent in HFE on Glass Substrateat 175° C. Coating 5 min 10 min 20 min composition: Bonding AbrasionBonding Abrasion Bonding Abrasion Wt % Solids after 2 after after 2after 2 hours after 2 after 2 hours Amine Curing hours in boiling hoursin in boiling hours in in boiling Agent, Wt % boiling (500 boiling water(500 boiling water (500 solids TEOS water cycles) water cycles) watercycles) Ex. 7-1 3 2 4 4 4 4 3 wt % RC5125 Ex. 7-2 3 2 4 4 4 4 3 wt %RC5125, 1.5 wt % TEOS Ex. 7-3 3 3 4 4 4 4 3 wt % BTMPA Ex. 7-4 3 3 4 4 44 3 wt % BTMPA, 1.5 wt % TEOS

TABLE 8 Test Results of Dried & Cured Coatings Prepared from 10 wt %PFE131 and RC5125 or BTMPA Amine Curing Agent in HFE on Glass Substrateat 140° C. and 300° C. Coating composition: 140° C. 300° C. Wt % SolidsAmine Bonding Bonding Bonding Bonding Curing Agent, before after beforeafter Wt % solids TEOS boiling boiling boiling boiling Ex. 8-1 3 2 3 3 3wt % RC5125, 1.5 wt % TEOS Ex. 8-2 3 2 3 3 3 wt % BTMPA, 1.5 wt % TEOS

TABLE 9 Advancing & Receding Contact Angle Test Results of Dried & CuredCoatings Prepared from 1 wt % PFE131 and Amine Curing Agent in HFE onGlass Substrate Cured at 160° C. Coating composition: Initial PropertiesAfter Abrasion Test (500 cycles) Wt % Solids Amine Curing H₂O HexadecaneH₂O Hexadecane Agent, Wt % solids TEOS Adv. Rec. Adv. Rec. Adv. Rec.Adv. Rec. Ex. 9-1 - Control - PFE131 127.8 90.6 72.6 53.8 17.1 5.5 NT NT1 wt % solids in HFE-7500 Ex. 9-2 - Control - PFE131 133.4 95.8 79.359.1 12.4 4.6 NT NT 2.5 wt % solids in HFE-7500 Ex. 9-3 - 3 wt % BTMPA,129.7 102.5 70.6 53.7 104.6 43.5 66.2 47.1 1.5 wt % TEOS Ex. 9-4 - 3 wt% RC5125, 126.6 97.6 76.5 59.8 107.9 52.2 70.3 47.0 1.5 wt % TEOS

TABLE 10 Advancing & Receding Contact Angle Test Results of Dried &Cured Coatings Prepared from 1 wt % PFE131 and Amine Curing Agent in HFEon Glass Substrate Cured at 160° C. After 2 Hours in Boiling After 2Hours in Boiling Water, After Coating composition: Water, BeforeAbrasion Abrasion Test (500 cycles) Wt % Solids Amine Curing H₂OHexadecane H₂O Hexadecane Agent, Wt % solids TEOS Adv. Rec. Adv. Rec.Adv. Rec. Adv. Rec. Ex. 10-1 - Control - 15.9 8.3 11.0 6.9 NT NT NT NTPFE131 1 wt % solids in FIFE-7500 Ex. 10-2 - Control - 14.8 4.7 12.3 5.6NT NT NT NT PFE131 2.5 wt % solids in HFE-7500 Ex. 10-3 - 3 wt % 126.471.2 69.2 47.8 123.0 73.5 72.8 46.2 BTMPA, 1.5 wt % TEOS Ex. 10-4 - 3 wt% 124.9 72.7 77.3 56.7 60.8 20.7 66.6 46.7 RC5125, 1.5 wt % TEOS

For the following table, the coating solutions were applied with a No.12 Meyer rod to the polycarbonate substrate (described in Table 1) andcured for 10 minutes.

TABLE 11 Advancing & Receding Contact Angle Test Results of Dried &Cured Coatings Prepared from 1 wt % PFE131 and Amine Curing Agent in HFEon Polycarbonate Substrate Cured at 140° C. Coating composition: BondingWt % Solids Amine after 2 Abrasion (200 cycles) Curing Agent, hoursBefore After Wt % solids TEOS boiling boiling boiling Ex. 11-1 -Control - PFE131 1 2 2 1 wt % solids in HFE-7500 Ex. 11-2 - 3 wt %RC5125 4 4 3 Ex. 11-3 - 3 wt % RC5125, 4 4 3 1.5 wt % TEOS Ex. 11-4 - 3wt % BTMPA 4 4 4 Ex. 11-5 - 3 wt % BTMPA, 4 4 4 1.5 wt % TEOS Ex. 11-6 -1.5 wt % APMS 3 4 4

Perfluoroelastomer Coating Solution Preparation:

10 wt % solutions of PFE131 with amine curing agents were prepared asdescribed above. Some of the coating solutions also contained TEOS asindicted in the Table below.

Perfluoroelastomer PFE-131T2 gum was obtained by a compounding process(PFE 131 gum filled with 30 wt % carbon black and the indicated aminecuring reagents). It was cut into pieces and dissolved in HFE-7500solvent by constantly shaking or stirring the solution overnight toobtain a 10 wt % PFE131T2 in HFE-7500 solution. To the PFE 131 solutionwas added the indicated amine curing agent(s) at the amounts describedin the Tables. The solutions were stirred under vortex for 1-2 min at2500 RPM.

Coating the Perfluoroelastomer Coating Solution onto a Substrate:

The coating solutions described in the following Tables were coated ontothe aluminum substrate (described in Table) by drop casting. Theresulting coating coatings were allowed to air dry and were subsequentlyplaced into an oven at 200° C. for 10 minutes. The thickness of thedried and cured coating was 1-2 mils. The coated substrates wereevaluated with the following Acid/Base Corrosion Tests.

Acid/Base Corrosion Tests:

Concentrated NaOH (33 wt %) and dilute HNO₃ (7 wt %) were prepared.Coated substrates were then separately placed in the NaOH and HNO₃solutions for 24 hours. The tested samples were taken out and rinsedwith water to observe if the aluminum was corroded.

TABLE 12 Corrosion Test - Concentrated Aqueous NaOH Coating composition:Wt % Solids Amine Curing Agent, Wt % solids TEOS Aqueous NaOH (33 wt %)Ex. 12-1 - Control Corroded 10 wt % PFE-131 (no amine curing agent) Ex.12-2 - 3 wt % BTMPA, Very lightly corroded at the edge 1.5 wt % TEOS(may be due to imperfect coating) Ex. 12-3 - 3 wt % RC5125, Not corroded1.5 wt % TEOS

TABLE 13 Corrosion Test -Aqueous HNO₃ Coating composition: Wt % SolidsAmine Curing Agent, Wt % solids TEOS Aqueous HNO₃ (7 wt %) Ex. 13-1 -Control Corroded along the edge 10 wt % PFE-131 (no amine curing agent)Ex. 13-2 - 3 wt % BTMPA, Not corroded 1.5 wt % TEOS Ex. 13-3 - 3 wt %RC5125, Slightly corroded at the edge 1.5 wt % TEOS

TABLE 14 Corrosion Test - Aqueous NaOH Coating composition: Wt % SolidsAmine Curing Agent, Wt % solids TEOS Aqueous NaOH (33 wt %) Ex. 14-1 -Control Not corroded 10 wt % PFE131T2 (no amine curing agent) Ex. 14-2 -3% BTMPA, Not corroded 1.5% TEOS Ex. 14-3 - 3% RC5125, Not corroded 1.5%TEOS

TABLE 15 Corrosion Test - Aqueous HNO₃ Coating composition: Wt % SolidsAmine Curing Agent, Wt % solids TEOS Aqueous HNO₃ (7 wt %) Ex. 15-1 -Control Not corroded 10 wt % PFE131T2 (no amine curing agent) Ex. 15-2 -3 wt % BTMPA, Not corroded 1.5 wt % TEOS Ex. 15-3 - 3 wt % RC5125, Notcorroded 1.5 wt % TEOS

These same corrosion tests were repeated with the same coatingcompositions and curing conditions utilizing carbon steel and stainlesssteel as the substrate, as described in Table 1. The corrosion testresults were substantially the same.

Samples were prepared by depositing the solutions with a No. 24 Meyerrod on PET films. The film was dried at ambient temperature for 2 hoursand at 50 C for 20 min. After the samples were completely dried, thecoated PET film samples were then placed on a wooden or a stainlesssteel board and UV cured by conveying the coated PET film samples at arate of 30 feet/minute with a UV curing system having a 500 watt H-bulbUV lamp. The step of conveying the samples though the UV curing systemwas repeated for a total of 10 exposures (or in other words 10 runs).After UV curing, the coated PET film is then thermally cured at 120° C.for 5 min in an oven. The cured samples were peeled off partially fromthe PET film were weighted and subsequently recorded, and then dissolvedin FIFE 7500 with a mass ratio of cured sample/HFE 7500=5/95 in a vial.The vial is subject to vigorous shaking overnight (˜12 hours) before anyobservation regarding the extent of crosslinking was recorded asdetailed in the following table. The precipitated samples remained inthe HFE-7500 solutions were collected, dried and weighted as being PFEcrosslinking product yields.

Extent of Crosslinking Description Soluble Completely soluble or most ofsample is dissolved Viscosity Partially soluble, HFE solution becomesviscous, builds up small amount of precipitate (like small flakes orsilks), inseparable Swell, Noticeable precipitation, largely~mediallyswell, low yield however a significant amount of sample is dissolved GelSample takes on the appearance of gel, largely swell, inseparable ordifficult to separate Swell Insoluble, apparent swell and increase involume, the HFE solution is viscous, inseparable or difficult toseparate Precipitate Completely insoluble, a little to no swell, Intactfilm, HEF has very low viscosity, separable

TABLE 16 Effect of an aminosilane ester on UV curing of PFE-40 Thermallycured at UV cured for 10 runs + Thermally 120 C. for 5 minutes cured at120 C. for 5 minutes Primary Amino silane Ex. 16 - 0.5% APES SolubleViscosity builds up Ex. 17 - 1% APES Soluble Gel 64.75 wt % Ex. 18 -1.5% APES Soluble Swell 84.72 wt % Ex. 19 - 3% APES Soluble Precipitate86.06 wt % Ex. 20 - 5% APES Soluble Precipitate 88.33 wt % Ex. 21 - 3%APES 2% TEOS Soluble Precipitate 86.80 wt % Ex. 22 - 3% APES 2% TMOSSoluble Precipitate 83.59 wt % Ex. 23 - 1.5% APES 1% 1173 Soluble Swell87.53 wt % Ex. 24 - 3% APES 1% 1173 Soluble Precipitate 91.26 wt % Ex.25 - 3% APES 2% 1173 Soluble Precipitate 86.69 wt % Ex. 26 - 5% APES 2%1173 Soluble Precipitate 87.92 wt % Ex. 27 - 5% APES 5% 1173 SolublePrecipitate Secondary Amino silane Ex. 28 - 1% N-ME-APMS SolubleViscosity builds up Ex. 29 - 2.5% N-ME-APMS Soluble Gel Ex. 30 - 5%N-ME-APMS Soluble Gel 85.60 wt % Ex. 31 - 5% N-ME-APMS SolublePrecipitate 80.61 wt % 0.5% APES Ex. 32 - 5% N-ME-APMS SolublePrecipitate 81.68 wt % 1% APES Tertiary Amino silane Ex. 33 - 1%BTMP-Me-A Soluble Viscosity builds up Ex. 34 - 5% BTMP-Me-A Soluble GelEx. 35 - 5% BTMP-Me-A Soluble Swell Primary + Secondary Amino silane Ex.36 - 3% TMP-ETDA Soluble Swell

TABLE 17 Effect of amines on UV curing of PFE-40 UV cured for 10 runs +Thermally cured at Thermally cured at 120° C. Primary amine 120° C. for5 minutes for 5 minutes Ex. 37- 5% Soluble Gel ethylenediamine Ex. 38 -1% Soluble Viscosity builds up ethylenediamine

TABLE 18 Effect of an aminosilane ester on UV curing PFE-60 UV cured for10 runs + Thermally cured at Thermally cured at 120 C. Primary Aminosilane 120 C. for 5 minutes for 5 minutes Ex. 39 - 5% APES Viscosityincrease Swell, 88.94 wt %Some of the compositions of Examples 16-39 were cured with a D-bulbinstead of an H-bulb and provided similar crosslinking results.

1. A composition comprising at least one fluoropolymer, wherein thefluoropolymer comprises at least 90% by weight based on the total weightof the fluoropolymer of polymerized units derived from perfluorinatedmonomers selected from tetrafluoroethene (TFE) and one or moreunsaturated perfluorinated alkyl ethers; solvent comprising a branched,partially fluorinated ether and wherein the partially fluorinated ethercorresponds to the formula:Rf—O—R wherein Rf is selected from perfluorinated and partiallyfluorinated alkyl or (poly)ether groups and R is selected from partiallyfluorinated and non-fluorinated alkyl groups; and a compound comprisingat least one amine group and at least one organosilane group.
 2. Thecomposition of claim 1 wherein the unsaturated perfluorinated alkylether has the general formulaR_(f)—O—(CF₂)_(n)—CF═CF₂ wherein n is 1 or 0 and R_(f) is aperfluoroalkyl or perfluoroether group.
 3. The composition of claim 1wherein the compound is an amino organosilane ester compound or esterequivalent.
 4. The composition of claim 1 wherein the compound comprisesa blocked amine group.
 5. The composition of claim 1 wherein thecomposition further comprises an alkoxy silane compound that lacks oneor more amine groups.
 6. The composition of claim 1 wherein thecomposition comprises 0.01 to 25% by weight of the fluoropolymer basedon the weight of the total composition.
 7. The composition of claim 1wherein the partially fluorinated ether of the solvent corresponds tothe formula:C_(p)F_(2p+1)—O—C_(q)H_(2q+1) wherein q is an integer from 1 to 5 and pis an integer from 5 to
 11. 8. The composition according to claim 7wherein the C_(p)F_(2p+1)-unit is branched.
 9. The composition of claim1 wherein the fluoropolymer comprises nitrile cure sites.
 10. Thecomposition of claim 1 wherein the fluoropolymer comprises one or morecure sites selected from iodine, bromine, chlorine, or a combinationthereof;
 11. The composition of claim 1 wherein the fluoropolymercomprises 40 to 60% by weight of polymerized units of TFE based on thetotal weight of the fluoropolymer.
 12. The composition of claim 1wherein the fluoropolymer contains 0 to 5 wt.-% of polymerized unitsderived from non-fluorinated or partially fluorinated monomers.
 13. Acomposition comprising at least one fluoropolymer, wherein thefluoropolymer comprises at least 90% by weight based on the total weightof the fluoropolymer of polymerized units derived from perfluorinatedmonomers selected from tetrafluoroethene (TFE) and one or moreunsaturated perfluorinated alkyl ethers; and one or more cure sitesselected from nitrile, iodine, bromine, or a combination thereof; afluorinated solvent; and a compound comprising at least one amine groupand at least one silane group.
 14. The composition of claim 13 whereinthe solvent has a GWP of less than
 1000. 15. The composition of claim 14wherein the fluorinated solvent is a branched, partially fluorinatedether and wherein the partially fluorinated ether corresponds to theformula:Rf—O—R wherein Rf is selected from perfluorinated and partiallyfluorinated alkyl or (poly)ether groups and R is selected from partiallyfluorinated and non-fluorinated alkyl groups.
 16. (canceled)
 17. Thecomposition of claim 1 wherein the composition lacks a free-radicalphotoinitiator.
 18. A method of making the composition of claim 1comprising dissolving the fluoropolymer in the solvent and adding thecuring agent subsequently, concurrently, or after dissolving thefluoropolymer in the solvent.
 19. A substrate comprising a coatedsurface wherein the coated surface comprises a crosslinkedfluoropolymer, wherein the fluoropolymer comprises at least 90% byweight based on the total weight of the fluoropolymer of polymerizedunits derived from perfluorinated monomers selected fromtetrafluoroethene (TFE) and one or more unsaturated perfluorinated alkylethers; and one or more cure sites selected from nitrile, iodine,bromine, or a combination thereof; and a compound comprising at leastone amine group and at least one silane group.
 20. (canceled)
 21. Apolymer sheet comprising a fluoropolymer wherein the fluoropolymercomprises at least 90% by weight based on the total weight of thefluoropolymer of polymerized units derived from perfluorinated monomersselected from tetrafluoroethene (TFE) and one or more unsaturatedperfluorinated alkyl ethers; and one or more cure sites selected fromnitrile, iodine, bromine, or a combination thereof; and a compoundcomprising at least one amine group and at least one silane group. 22.(canceled)
 23. A method of making a coated substrate comprising: i)applying a coating composition to a substrate wherein the coatingcomposition comprises at least one fluoropolymer, wherein thefluoropolymer comprises cure sites and at least 90% by weight based onthe total weight of the fluoropolymer of polymerized units derived fromperfluorinated monomers selected from tetrafluoroethene (TFE) and one ormore unsaturated perfluorinated alkyl ethers; fluorinated solvent, andan amine curing agent; ii) removing the solvent; and iii) curing thefluoropolymer at a temperature ranging from 135° C. to 170° C. or curingthe fluoropolymer with ultraviolet radiation concurrently or prior toremoving the solvent. 24-32. (canceled)